Looks like there was a boo boo in the December CTP of WPF/E and it prematurely time bombed. Tim Sneath has the details and links to the download for the latest Feb CTP:
(Thank goodness this didn't happen to me yesterday as I was presenting an MSDN event in London on WPF/E - could have made an interesting 75 minutes)
Also on the download front, Expression Blend Beta 2 and Design Beta 1 have been released. Head over to the Microsoft.com Expression site to get the latest bits.